This is a totally different beast +Richard Chu
and +Olivier Guéry
. Those Chromebooks run a 4-PLUS-1 Cortex-A15 model of Tegra K1 with a Kepler based GPU and IKS. Tegra X1 is 4 big Cortex-A57 and 4 little Cortex-A53 with a Maxwell based GPU -- What's so different? A LOT.
It's probably limited to cluster switching rather than hetrogeneous operation but the difference between cores and ISA used in Tegra 4 and K1: you may as well be comparing Pentium 4's versus Core i5's.